The present invention relates to a device for detecting when an intravenous or arterial cannula enters a vein or artery, and more particularly to a visually observable membrane which inflates or moves when the cannula comes into contact with the pressure of blood within a vein or artery.
Present intravenous and arterial cannulas depend upon a visual observance of blood itself in the hub of the cannula after the blood has flowed through the length of the cannula in order to indicate that the cannula needle has entered the vessel. Often, a cannula may puncture a blood vessel through both walls. When this happens using present cannulas, any back flow of blood may not be observed and the double puncture is undetected. This may result in improper administration of medication, hemorrhaging, collapse of the vein or artery, or other similar complications.
One method of addressing this situation is disclosed in U.S Pat. No. 5,030,207 to Mersch, et al. The Mersch device provides a fiber optic mounted around the cannula of the needle that is conformed to the distal end of the needle, so that as the distal end comes into contact with the blood at the interior of the vein or artery, that color is transmitted along the fiber optic to a magnifying system. However, the Mersch invention is complicated to manufacture, requires a certain amount of light to work properly, and may still allow the needle to puncture both walls of the vein or artery without being readily detected. The present is more reliable because it is activated by the pressure of the blood within the vessel.